Variable Connectivity Model for Determination of pKa Values for Selected Organic Acids

Matevž Pompe*,1 and Milan Randić2
1 Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia,
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2 National Chemical Institute, Hajdrihova 19, 1000 Ljubljana; 3225 Kingman Rd. Ames, IA 50014, USA;

A variable anti-connectivity topological index was optimized for the modeling of pKa values. The variable anti-connectivity index of order one showed superior modeling capabilities compared to ordinary variable connectivity index of the same order because it is capable to account for the combination of positive and negative contributions for the molecular descriptor in structure-property-relationship. Additionally we examined functional dependence of individual bond contributions on modeling property by varying also the exponent appearing in connectivity index. Such variation did not make significant improvements of the calculated results.

Keywords: Anti-connectivity, variable connectivity index, pKa, prediction.